This is a common homework question for students when they are learning unit conversions. This example problem shows how to calculate when the reading on a Celsius thermometer would equal the reading on on a Fahrenheit thermometer.

Start with one of the two conversion factors between °C and °F.

The two conversion formulas are:

°C = 5⁄9(°F – 32) and °F = 9⁄5°C + 32

It doesn’t matter which one you use since they are the same equation. Let’s use the second one. We want to know when °C = °F, so the equation becomes: